linux-kernel - Re: [PATCH v2 10/44] mmap: Change do_mas_munmap and do_mas_aligned

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Message-ID: <20230110172624.fuxgm7jpimskzgvs@revolver>
Date:   Tue, 10 Jan 2023 17:26:39 +0000
From:   Liam Howlett <liam.howlett@...cle.com>
To:     Sven Schnelle <svens@...ux.ibm.com>
CC:     "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "linux-s390@...r.kernel.org" <linux-s390@...r.kernel.org>
Subject: Re: [PATCH v2 10/44] mmap: Change do_mas_munmap and
 do_mas_aligned_munmap() to use vma iterator

* Sven Schnelle <svens@...ux.ibm.com> [230110 09:54]:
> Liam Howlett <liam.howlett@...cle.com> writes:
> 
> > From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
> >
> > Start passing the vma iterator through the mm code.  This will allow for
> > reuse of the state and cleaner invalidation if necessary.
> >
> > Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
> > ---
> >  include/linux/mm.h |  2 +-
> >  mm/mmap.c          | 77 +++++++++++++++++++++-------------------------
> >  mm/mremap.c        |  6 ++--
> >  3 files changed, 39 insertions(+), 46 deletions(-)
> >
> 
> Starting with this patch i see the following oops on s390:
> 
> [    4.512863] Run /sbin/init as init process
> [    4.519447] Unable to handle kernel pointer dereference in virtual kernel address space
> [    4.519450] Failing address: fbebfffb00000000 TEID: fbebfffb00000803
> [    4.519452] Fault in home space mode while using kernel ASCE.
> [    4.519455] AS:0000000001a60007 R3:0000000000000024
> [    4.519482] Oops: 0038 ilc:2 [#1] SMP
> [    4.519486] Modules linked in:
> [    4.519488] CPU: 7 PID: 1 Comm: init Not tainted 6.2.0-rc1-00179-ga7f83eb601ef #1582
> [    4.519491] Hardware name: IBM 3906 M04 704 (z/VM 7.1.0)
> [    4.519493] Krnl PSW : 0704c00180000000 0000000000929464 (__memcpy+0x24/0x50)
> [    4.519503]            R:0 T:1 IO:1 EX:1 Key:0 M:1 W:0 P:0 AS:3 CC:0 PM:0 RI:0 EA:3
> [    4.519506] Krnl GPRS: 0000000000000000 0000037fffb1f990 0000037fffb1f990 fbebfffb00000008
> [    4.519509]            0000000000000007 0000000000929480 0000000000000008 0000000000000000
> [    4.519517]            0000000000000009 0000037fffb1fb40 0000037fffb1f880 0000037fffb1fc58
> [    4.519519]            0000000080288000 0000000000000001 0000000000cf65da 0000037fffb1f5d8
> [    4.519527] Krnl Code: 0000000000929456: b9040012            lgr     %r1,%r2
> [    4.519527]            000000000092945a: a7740008            brc     7,000000000092946a
> [    4.519527]           #000000000092945e: c05000000011        larl    %r5,0000000000929480
> [    4.519527]           >0000000000929464: 44405000            ex      %r4,0(%r5)
> [    4.519527]            0000000000929468: 07fe                bcr     15,%r14
> [    4.519527]            000000000092946a: d2ff10003000        mvc     0(256,%r1),0(%r3)
> [    4.519527]            0000000000929470: 41101100            la      %r1,256(%r1)
> [    4.519527]            0000000000929474: 41303100            la      %r3,256(%r3)
> [    4.519547] Call Trace:
> [    4.519548]  [<0000000000929464>] __memcpy+0x24/0x50
> [    4.519557]  [<0000000000cfd474>] mas_wr_bnode+0x5c/0x14e8
> [    4.519562]  [<0000000000cffaf6>] mas_store_prealloc+0x4e/0xf8
> [    4.519569]  [<000000000039d262>] mmap_region+0x482/0x8b0
> [    4.519572]  [<000000000039da6e>] do_mmap+0x3de/0x4c0
> [    4.519575]  [<000000000036aeae>] vm_mmap_pgoff+0xd6/0x188
> [    4.519580]  [<000000000039a18a>] ksys_mmap_pgoff+0x62/0x230
> [    4.519584]  [<000000000039a522>] __s390x_sys_old_mmap+0x7a/0x98
> [    4.519588]  [<0000000000d22650>] __do_syscall+0x1d0/0x1f8
> [    4.519592]  [<0000000000d32712>] system_call+0x82/0xb0
> [    4.519596] Last Breaking-Event-Address:
> [    4.519596]  [<0000000000cf65d4>] mas_store_b_node+0x3cc/0x6b0
> [    4.519603] Kernel panic - not syncing: Fatal exception: panic_on_oops
> 
> This happens on every boot, always killing the init process. The oops
> doesn't happen with next-20230110. With next-20230110 i see shmat
> testcase failures in ltp (shmat returning with -EINVAL because
> find_vma_intersection() tells shmat that there's already a mapping
> present).
> 
> Trying to bisect that i stumbled above the oops above. Any ideas before
> i start trying to understand the patch?

Yes, try the patch for fixing the invalidated state I sent out yesterday
[1].  This should come before ("mm: expand vma iterator interface").

1. https://lore.kernel.org/linux-mm/20230109165455.647400-1-Liam.Howlett@oracle.com/